篮球竞彩在哪玩 :CIMSՓĵ

򾺲 www.fasfz.com  

MICROSTRUCTURE EVOL UTION IN THE PREPARATION OF CARBON AEROGELS BY SMALL ANGLE X-RAY SCATTERING

ע⣺Փڡ̼ϡ2002,17(3):31C36l
ʹՈעՓij̎
ZHANG Rui 1 , XU Yao 1 , LU Yonggen 1 , LI Zhihong 1 , MENG Qinghan 1 , LI Kaixi 1 , WU Dong 1 , LING Licheng 1 , WANG Jun 2, ZHAO Hui 2 , RONG Lixiang 2 , DONG Baozhong 2
(1. State Key Laboratory of Coal Conversion , Institute of Coal Chemistry , Chinese Academy of Sciences , Taiyuan 030001 , China ;
2. Institute of High Energy Physics , Chinese Academy of Sciences , Beijing 100039 , China)

Abstract:Solgel polymerization of phenolic resole and methylolated melamine in basic aqueous solution at 85 for 5 days led to the formation of hydrogels , which , after water in the hydrogels was exchanged with acetone , were dried under supercritical carbon dioxide to produce organic aerogels . Carbon aerogels were obtained by pyrolyzing these organic aerogels at 850 for 3 h in nitrogen. Microstructure evolution during the preparation was followed by small angle X-ray scattering. It is found that hydrogel is monodispersed , swelled by water , and has a sharp peak in the scattering intensity profile , indicating a spatial periodical nanostructure formed by nanoscale phase separation via spinodal decomposition. After solvent exchanging , the acetone gel thus obtained is also monodispersed , but is partly deswelled , and has a shoulder2like scattering peak. This is a result of a substantial increase in scattering intensity near the lower limit of the scattering vector , q caused by domain growth of the scattering entity. After supercritical carbon dioxide drying , the organic aerogels produced are polydispersed and deswelled completely by removal of the solvent. The peak in the scattering intensity profile disappears completely by further growth of domains as a result of the structural relaxation from an unstable to a more stable state , induced by an increase in instability of the gel formed by supercritical drying. Moreover , a diffuse interface layer characterized by negative deviation from the Porod law is found in organic aerogels . After pyrolysis , the polydispersion is retained in the carbon aerogel , however , the diffuse interface layer disappears due to migration of the layer to particles to reduce the interface energy. Also in this process , joint actions of further growth in domain size and volume reduction by mass loss and densification slightly broaden the distribution of the radius of gyration of scattering entities , and shift the most probable peak radius of gyration to the small size direction.
Keywords: Carbon aerogel ; Pyrolysis ; Small angle X-ray scattering ; Microstructure

С X 侀ɢоƂ̿z^z΢Yݻ

1 , ҫ1 , 1 , ־1 , ϑc1 , _ϲ1 , |1 , 1 , 2 , w x2 , sϼ2 , 2
(1. ЇƌWԺ ɽú̿Wо , ɽ ̫ԭ 030001 ; 2. ЇƌWԺ о , 100039)


ժ Ҫ: ȩ֬u׻۰ډAˮҺ 85 ˮԡз 5 d z - z^γˮzˮ zͪÓQaͪz ,󽛳R̼ЙCzЙCzڵ 800 ѽ 3 h γ̿zС X - 侀ɢ似gɢՓķNz΢YM˷YlF:ˮ zdžηɢ ,ˮÛ 0. 15 nm ̎Џɢ ,м{׳߶ȵĿgڽY ,@NYͨ ^B{׳߶׃ ΢xaɱͪÓQaͪzҲdžηɢ ,ͪ΢Û 0. 15 nm м ,ˮz܄ÓQ^аlp΢FۮaĴ^С̎lҵɢʹ ݻɼЙCz̿zǶɢ ,С̎]ɢ ,ڳR^ӵĈF ^ml¶ɢԲw˼{׳߶ȵĿgڽYʹɢʧЙCzдڵĔUɢ ѽ^ʧ ,@ѽ^ДUɢwԽͽС X - 侀ɢ 䔵 Shull2Roess õЙCz̿zĻD돽ֲ^֪ ,ѽ^ ,ӵĈFL |pʧܻͬõĽYʹ̿zĻD돽ֲЙCzԌ ,Ɏ׻D돽΢pС
PI~: ̿z;ѽ;С X 侀ɢ;΢^Y

 

1g[PDFʽȫҪʹܛAbode Acrobat(ܛ^󲢳Ҋ,վṩd)

2dՓȫՈcI顱ʹÔcmܛd(168KB)


վ䛵ıߵՓģ

1Preparation of Porous Carbon Microspheres

2Preparation of mesocarbon microbeads from coal tar

3÷Qطо۱ϩ֬^

4׷ȩ֬̿Ƕо

5۱ϩwSA^еĽY͟D׃

6gr̼΢Ƃ估ǶОо

PՓՈcվ<<<վȫ>>>

gӭӑՓlՓļоIĿ
(Ոڰlԕrژ}ʹcuՓĵ}Ŀо@ӷҞg[)

| CIMSՓ | й | ̓M | | Փ | Ŀ_l | WgYԴ | վȫ | MՓľWվȫ |

line.gif (4535 ֹ)

˸õĞҷgӭӱվͶƱ{

򾺲 Ոc

վ򾺲 gӭL

ע⣺վδSDd

All rights reserved, all contents copyright 2000-2019
վ20003¿WL